The invention concerns a ballooning action constraining ring made of a material which is suitable for absorbing lubricant, the thread contact surface of which ring is such that the friction stress on the threads is decreased by means of the thread contact surface.
The problem which occurs upon the working up of fibers, particularly with the working up of synthetic fibers, specifically polyester fibers, on ring spinning machines, is known from Melliand Textilberichte, 1979, pp. 297/298. With use of the previously customary ballooning action constraining rings, losses in tensile strength and elongation occur in the yarn, which amount to about 30-50% of the tensile strength and elongation, which are obtained when the same yarn is produced with a working-up speed about 15-20% smaller. Moreover, there is found therewith, in customary manner, a strong roughening of the yarn with fiber injury, which leads upon its further working up to a strong fiber fraying. With the use of the previously customary ballooning action constraining rings there occurs in other respects tensile strength and elongation differences in the prepared yarn between the thread sections developed in the upper region (cop tips) and in the lower region (cop base) of the cop, which leads to differences in dye affinity, and which, particularly with colored knitwear, has a disturbing effect by means of the thereby effected curl formation. In order to obtain an increase in production without injury to the yarn, for decreasing the friction stress of the thread at the ballooning action constraining ring, it has been suggested to either completely lubricate the threads themselves before contact with the ballooning action constraining rings or to use a lubricated ballooning action constraining ring. The invention is therefore concerned with a ballooning action constraining ring which can be used as a lubricated ballooning action constraining ring.
A lubricated ballooning action constraining ring with an oil distribution groove and a lining disposed therein is known from Chemifasern/Textilindustrie, August 1975, page 669, left column, second from last paragraph and FIG. 2, which lining is disposed at a radial distance from the threads to be lubricated, so that no direct contact takes place with the threads, but only the distant fibers brush against the oil-furnishing lining and the lubricant is brought in sparingly dosed amounts between the threads and the ballooning action constraining ring. The oil distribution groove with the lining is, for this reason, considered in the direction of course of the threads, disposed before the contact surface between thread and ballooning action constraining ring. The supply of lubricant to the lining disposed in the oil distribution groove can follow therewith by means of a wick. This known ballooning action constraining ring is complicated in construction and has moreover the disadvantage that indeed according to the number and length of the distant fibers of the thread to be lubricated, different amounts of lubricant are brought between the thread and the ballooning action constraining ring. This can have as a result that with shorter and less distant fibers, the lubrication is not sufficient, and with many and long-distanced fibers the amount of lubricant absorbed by the thread is too great. With this known ballooning action constraining ring a precise adjustment of the distance between thread or "thread balloon" and the lubricant-soaked lining to the thread characteristics (length and number of the distant fibers) is thus necessary. A further disadvantage possessed by these known ballooning action constraining rings is that a sufficient lubricant film is first adjusted after a long operational period, whereby upon starting-up of the apparatus the surface of the ballooning action restraining ring contacted by the thread is initially still dry, i.e. unlubricated. The formation of the lubricant film occurs as follows: A part of the lubricant absorbed by the distanced fibers of the thread is transferred by the contact surface of the ballooning action constraining ring. Since then, however, the thread, and not only the distanced fibers are in contact with the ballooning action constraining ring, a part of the lubricant delivered by the fibers is again absorbed and transported away by the other parts of the thread from the contact surface. An equilibrium state is then obtained when the same amount of lubricant is delivered per running meter of thread length at the contact surface is absorbed and transported away by the thread. Since with the known ballooning action constraining ring the lubricant however is brought only "in sparsely dosed amount" between thread and ballooning action constraining ring, it generally takes a very long time until such an equilibrium condition is obtained. A more considerable further disadvantage with these known ballooning action constraining rings is that they are not suitable for the working-up of filament yarns, since with these the distanced fibers responsible for the transport of lubricant are missing. These known ballooning action constraining rings have, probably for this reason, and if necessary still further disadvantages, not been able to be employed unlimitedly in practice.
A further disadvantage is that the lining of these known ballooning action constraining rings is quickly dirtied, whereby the oil delivery can quickly decline to the thread, so that this ballooning action constraining ring must be cleaned regularly and at brief time intervals during operation. A self-cleaning effect by means of the thread does not occur, since the contact only with the distanced threads is obviously not sufficient.
From German Auslegeschrift No. 2,351,974 there is known a tube-shaped ballooning action limiter for thread machines, the interior wall of which, stroked over by the thread balloon, is composed of a sinter substance of a plastic basis and indeed of low pressure polyethylene which, based upon its pore size, has a capillary action. As a result of the capillary action of the sintered polyethylene material the dosaging for the sliding film formation can be very finely undertaken, and indeed through choice of a suitable capillarity. The material employed therewith is absorbent, i.e., it has the capacity, based upon capillary action, to move liquids. The sinter material of low-pressure polyethylene basis has preferably a density of 0.61-0.66 g/cm.sup.3 and a porosity of 27-35%. The mentioned reference teaches, moreover, that the material, based upon its pore size, has a capillary action; however no concrete statements are provided. Tests with ballooning action constraining rings of commercially obtainable sinter materials of low-pressure polyethylene yield based upon too small a resistance to wear or too high a lubricant delivery, results which are not useful for operational employment.
A further ballooning action constraining ring suitable for a storage of lubricant as detailed above, which is composed of a material which is suitable for absorbing lubricant and which so delivers at the fiber contact surface, that the friction stress of the thread is decreased by means of the thread contact surface is likewise known from Chemifasern/Textilindustrie, August 1975, p. 669, left column, last paragraph and right column, first paragraph. The raw material is sinter metal. In practice, it has however turned out that indeed for a short duration (a few days) the friction stress of the thread is decreased as a result of the lubricated ballooning action constraining ring, so that in order to maintain this activity the lubricant must be regularly replenished. The thread is therewith coated with lubricant, whereby a dirtying of the machine occurs. Frequent additional re-filling and cleaning work on the machine is a result. A wick embedded in this ring at the outside of the ballooning action constraining ring extends the refilling interval, but promotes more cleaning work, since the wick is quickly dirtied. Tests with ballooning action constraining rings of commercially customary sinter metals lead, based upon too high a lubricant delivery and more regular dirtying of the wick and also the entire machine, to results which are not useful.